Self-sealing, gas-proof elastomeric closures or configurations are used extensively for sealing an open end of an air-evacuated blood collection tube. These types of closures not only provide an effective seal for maintaining a vacuum inside the collection tube, but are also penetrable by a cannula so that fluids may be deposited or withdrawn from the container without compromising the sterility of the inside of the container. While these types of closures have been utilized for a long time, improvements in their use and features are continually being made. For example, U.S. Pat. No. 4,111,326 explains many of the deficiencies of these prior closures, while offering improvements over these prior art closures, such as the use of less material for construction, reduction of manufacturing expense, easier assembly, and a much lower force needed to penetrate with a needle.
In addition to the many deficiencies of prior art closures, as pointed out in U.S. Pat. No. 4,111,326, other problems arise in the use of the air-evacuated blood collection tube. Specifically speaking, some blood collection tubes are inoperable due to the fact that something has caused the vacuum condition inside the blood collection container to dissipate. These collection tubes, sometimes referred to in the art as "dead tubes", are not only non-functional, but also are sometimes undetectable when "dead". In many instances, it is not until the user of the collection tube is attempting to collect blood that it is realized that there is no vacuum inside the container.
As a result, U.S. Pat. No. 4,293,078 provides a vacuum indicator closure for a blood collection tube. This device seals the open end of an air-evacuated blood collection tube and includes a tubular flexible elastomeric body having an open first end and a closed second end. The second end is formed by a cannula-penetrable, flexible elastic end wall having an outer surface and an inner surface. The outer surface of the end wall is convexly curved and the inner surface is concavely curved when pressure on both the inner and outer surfaces is equal. This end wall is sufficiently flexible to deflect under the influence of a pressure differential on the end wall so that when the pressure against the outer surface exceeds the pressure against the inner surface, the outer surface becomes concavely curved and the inner surface becomes convexly curved. This condition occurs when there is a vacuum inside the blood collection tube. The outer surface of the end wall is readily visible to an observer with its changeable nature serving as an indicator of relative pressures on the opposite sides of the end wall. A flange is annularly disposed around the periphery of the tubular body adjacent to the second end.
In usage, this device has been highly effective and is otherwise known as a "VACUTAINER" (TM) seal. Unfortunately, this closure is utilized only with standard glass blood collection tubes. Standard glass blood collection tubes have a variety of problems that make them unsuitable for the purposes contemplated by the makers of the closures for such tubes. As with any glass material, the glass blood collection tube is subject to a relatively easy breakage. Such breakage can destroy the sample collected within the tube and can cause other problems, i.e., injury, contamination of environment, exposure of individuals and environment to potential health hazards within the labs. Furthermore, this breakage potential is exacerbated by the fact that a great deal of pressure is required to join the closure to the open end of the blood collection tube at the time of manufacture. There have been a number of incidents in which the collection tube has broken upon the attempted removal of the closure from the tube. This presents an additional hazard to health care personnel.
Where glass collection tubes are utilized, shipment through the mail becomes quite difficult. In order to ship such extremely breakable material in the mail, a relatively complex shipping box must be developed. A great deal of cushioning-type material must be placed between each of the tubes in the potential shipment. In normal operations utilizing the standard postal services, boxes containing such tubes can be thrown about, compressed, or otherwise damaged. As a result, such blood collection tubes become broken and damaged during the shipment between the collection site and the lab. Furthermore, the labor requirements for assembling the shipping containers is a disadvantage to the use of such glass tubes. An ideal situation would be to simply enclose the blood collection tube in a box, or an envelope, seal the envelope, and send the collected blood to the lab.
With the spread of the AIDS virus, and other dangerous infectious diseases, it is extremely important that collected blood be maintained in a sealed environment. AIDS-contaminated blood can be a potential health hazard to those that would handle such glass collection tubes, especially lab personnel. Lab personnel are especially at high risk for exposure to contaminated blood because it requires a significant amount of pressure to remove the closure from the blood collection tube because of the manufacturing procedures (which require precise insertion and mating of the closure to the tube). Since removal must occur in the laboratory for analysis of the sample, injury can occur and does frequently.
As with most glass manufacturing operations, there are manufacturing difficulties in providing the tolerances required for the engagement of the closure of U.S. Pat. No. 4,293,078. Many times, the flow characteristics of glass cause dimensional differences between the closure and the open end of the glass tube. This may limit the ability to cause and to maintain a vacuum within the blood collection tube. In practice, those glass tubes that are manufactured in a relatively inaccurate and imprecise way must not be used. If they are not used, then the seal between the closure and the tube would be inadequate and would allow the loss of a vacuum.
It is known that glass is a less than adequate material for the containing of blood. Glass inherently contains many impurities. The trace elements and background materials within the glass of the tube can leach into the blood and be detected in the testing procedures. For example, there are many trace elements in the blood for which testing is carried out. However, when glass is used for the collection of the blood, the trace elements in the glass will diffuse into the blood and be of much higher levels than those trace elements that were in the original blood sample. The leaching of these trace elements into the blood can create many improper results in blood studies, cause misdiagnosis and mistreatment, or otherwise interfere with proper analytical techniques. As a result, the glass blood collection tubes can contribute to the inaccuracy of the blood studies.
Additionally, since glass is an extremely smooth material, there is not a great deal of friction between the surface of the closure and the inner surface of the blood collection tube. When the test tube has been manufactured with imprecise tolerances, the low amount of friction between the glass and the closure can allow the closure to slide outwardly from the open end of the glass tube and cause vacuum failure. In an effort to overcome this problem, the closure is made with an extremely long internal sleeve so as to engage the interior walls of the tube.
U.S. Pat. No. 4,856,533, issued on Aug. 15, 1989, to Anraku et al. describes a vacuum blood collection tube that is made of a polyethylene terephthalate material. Similarly, U.S. Pat. No. 4,735,832, issued on Apr. 5, 1988, to Ichikawa et al. describes a container made of a synthetic resin that could be used for containing blood. Both of these prior art patents describe the use of a liner material that is used for coating the interior of the tube. The purpose of this liner is to assist in the clotting of blood within the container. Since each of these prior art patents uses a liner material, this means that more material is used then is really needed to initiate the clotting action. Because of that, there may be some leaching of the material into the blood. The tubes of these prior art patents are injection blow molded. They are also lined with a less permeable plastic. As a result, the interface between the tube wall and the liner contributes to gas permeation.
During blood collection activities, it is usually desirable to have the blood clot within the tube. Silicon within the glass of a glass collection tube initiates this clotting function. When plastic is used as the tube, such as in these aforementioned prior art patents, silicon is not present and blood will have a tendency to not completely clot. Therefore, U.S. Pat. Nos. 4,856,533 and 4,735,832 utilize such lining materials to assist in this function. The use of a liner material, in addition to the problems stated hereinbefore, is difficult to apply, adds to the manufacturing expense, often does not effectively assist in the clotting of blood, and is more likely to be leached into the blood.
After experimentation, it was found that the closure of U.S. Pat. No. 4,293,078 was effective for maintaining vacuum in a glass blood collection tube. However, the tradeoff for the maintenance of this vacuum was that the closure of U.S. Pat. No. 4,293,078 makes it difficult to collect blood in an efficient ergonomic fashion. That is, the angle between the needle and the closure was such that it could not be used simply and easily by medical personnel for entering a vein. The extended interior sleeve of the closure and the extended exterior end of the closure requires that the needle be aligned away from the edges of the tube. As such, the closure of U.S. Pat. No. 4,293,078 presents an awkward angle for the collecting of blood from a vein. This makes it difficult, at times, for the needle to be slid a little way into the vein, as phlebotomists like to do. The needle may penetrate through the vein and into the back side of vein.
In order to collect blood, it is necessary to use an appropriate holder. These holders are typically identified as the "TERUMO VENOJECT" holders. This standard appliance receives the needle in a threaded opening at one end of the holder. This threaded opening is centered in an end surface at the end of the holder. The opening includes a double thread for the receipt of the needle. When the needle is attached, the blood collection tube is then placed within the holder so that one end of the needle will penetrate the closure. The vacuum of the closure will then cause blood to be sucked through the other end of the needle and into the collection tube.
The shape of the holder of the blood collection tube can cause additional problems. The small handles on the holder makes it difficult to turn the container so as to get a good angle. Also, the use of the double threaded opening means that the taper at the end of the needle can have a different angle to the vein depending on which of the "double threads" the needle body engages. In the collection of blood, for the safety and efficiency of the operation, it is desired that the longest end of the taper be at the lowermost position and that the needle be positioned nearly parallel to the vein.
It is an object of the present invention to provide an improved blood collection tube that has less breakage potential and stronger impact resistance.
It is another object of the present invention to provide a blood collection tube that simplifies procedures for the shipment of such tube.
It is a further object of the present invention to provide a blood collection tube that allows for manufacture with greater quality control, improved tolerances, greater efficiency, and less expensive procedures.
It is still a further object of the present invention to provide a blood collection tube that creates better fit between the open end of the tube and the closure.
It is another object of the present invention to provide an improved closure for a blood collection tube that allows the blood collection needle to assume a proper angle with respect to the vein.
It is another object of the present invention to provide an improved holder for a blood collection tube that causes the needle end taper to always assume the same position when used.
It is still a further object of the present invention to provide a blood collection system in which blood is collected in a safe, efficient, and consistent manner.
It is still another object of the present invention to provide a blood collection system that provides ease of use with decreased risk to the collector and patient.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.